Then there are those days, a handful of times a year, when he has to stop what he is doing, lie down in a dark room and try to sleep through the vision loss in his left eye, intense nausea and a severe headache.

Letang knows when he starts having impaired vision that he is at the onset of a migraine, but it is unnerving each time.

The vision problems and nausea that caused him to be violently ill subsided enough over about 20 minutes for Letang to join the pregame warmup. Despite recurring symptoms, he played 18 minutes, 18 seconds, getting an assist in the third period of a 6-5 shootout win against the Senators.

"It was kind of a big one," said Letang, 20, who has had migraines since he was about 12. "During the game, it came back because the lights were too bright for me."

Letang, who has played in five games since being recalled from Wilkes-Barre/Scranton, has been fine since the Ottawa game. He had an increased role in the 5-0 win Saturday against Atlanta after defenseman Sergei Gonchar left with a groin injury. After Gonchar left, Letang played the point on the top power-play unit. He logged 24:09 of ice time. There is no reason to think he will not be at full strength Friday when the Penguins play host to Dallas.

The episode last week was the second time he has had a migraine close to game time. He had one last season before a junior hockey all-star game, but it was not a severe one, and he played.

"It's still scary because they can [get worse] as I get older," Letang said. "When I was younger, they weren't that bad."

Letang's migraines typically last 25 to 30 minutes.

Various estimates and studies indicate as many as one in every four American households has someone who gets migraines, and it is believed many people who have them -- particularly men -- remain undiagnosed.

Former Dallas Cowboys quarterback Troy Aikman, now a Fox television analyst, has said he has had migraines for years but they were not diagnosed until after he retired from playing.

Migraines stem from a vascular problem, when blood vessels get constricted. They can be caused by vascular spasms after concussions or other injuries, but his appear to stem from heredity.

"My mom started having them when she was young," he said.

Symptoms can vary, and it is difficult to determine what triggers migraines. Letang said a doctor once told him exercise and increased heart rate can be a factor, but, as a high-level athlete, he regularly works out strenuously but can go as long as four months without one.

Penguins general manager Ray Shero said the club became aware that Letang was prone to migraines last season.

"But last week was the first time it became an issue because he almost couldn't play in a game," said Shero, who could not recall previously being in an organization with a player who dealt with migraines. "You just have to be on top of it. We just want to make sure he's OK."

Stewart, the first person players seek if they have a medical problem, has seen migraines in athletes before. His biggest concern would be if Letang develops vision problems while playing.

Penguins physicians likely will run tests to make sure there are no underlying problems and will monitor Letang to see if medications can help, Stewart said. Most migraine medications have to be taken at the earliest signs of an impending attack, and not everyone benefits from them.

"Sometimes neck massages help, but, if medication doesn't help, you just have to ride them out, get through the sickness," Stewart said. "Sometimes, they get nasty. It's one of the toughest things we deal with because there's not much you can do for him. You feel bad."

Letang has a standard procedure.

"Usually, I go to bed," he said. "I shut all the lights off and close all the shades and just go to sleep. If I wake up all the time during my migraine, I'm going to throw up."

Although his have gotten worse over the years, Letang hopes he outgrows them,.